The present invention relates to a thermal protection sheath and its fabrication method.
Thermal protection sheaths are routinely used to insulate fluid pipes, for example in automobile vehicles, and in particular in hydraulic circuits, fuel lines, brake fluid lines, cooling fluid lines and conditioned air lines.
This kind of thermal protection sheath includes a substrate covered with a reflective material adapted to reflect infrared radiation.
The substrate must be sufficiently flexible to adapt to various shapes of pipe and cover them without creasing.
A first technique for covering the substrate with a reflective material consists in applying a coating containing particles of aluminum, for example, directly to the outside surface of the substrate.
This kind of aluminized coating preserves good flexibility of the substrate of the protective sheath but has limited reflection properties. This is because the binder used to fix the aluminum particles to the surface of the substrate absorbs some thermal radiation and thereby limits the reflective power of the aluminized coating.
A second technique consists in fixing a reflective foil, such as aluminum foil or aluminized film, to the outside surface of the substrate.
These foils and films improve the thermal protection provided by the sheath but lack flexibility. In particular, the foils tend to tear if the sheath is deformed, and in particular if it is stretched.
U.S. Pat. No. 5,660,899 describes a thermal protection sheath comprising a substrate formed by a corrugated plastics material tube covered with a laminated structure glued at all points to the outside surface of the substrate.
The laminated structure and the substrate therefore have exactly the same corrugated tube form and the laminated structure and the substrate are in contact over their entire surface.